Liquid crystal display device

ABSTRACT

A liquid crystal display module includes an observation region to allow a visual inspection be performed after bonding of the substrates for inspecting the sealant that may be otherwise blocked by the common voltage line. An embodiment of a liquid crystal display device includes a first electrode on a first substrate, a second electrode and a third electrode on a second substrate, the second electrode electrically contacting the first electrode at a first portion and the third electrode at a second portion, and including a transparent conductive material, a sealant attaching the first and second substrates together in a sealant region, the sealant between the first and second electrodes and the sealant including a plurality of conductive balls for electrically connecting the first and second electrodes, and a liquid crystal layer between the attached first and second substrates and within the sealant.

The invention claims the benefit of Korean Patent Application Nos.10-2006-0061597 and 10-2007-055705 filed in Korea on Jun. 30, 2006 andJun. 7, 3007, which are hereby incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention relate to a liquid crystal display device,and more particularly, to a liquid crystal display device that allowseffective visual inspections of a sealant and prevents defectgenerations in a sealant.

2. Discussion of the Related Art

Cathode Ray Tubes (CRTs), which are traditionally utilized asinformation display devices, have advantages in functions and cost, buthave disadvantages in size miniaturization and portability. On the otherhand, recent advancement in semiconductor technology has allowed liquidcrystal display (LCD) devices to have better functions. In particular,LCD devices advantageously become smaller and lighter and consume lowpower, and accordingly receive attentions as replacement for overcomingthe disadvantages of the CRTs. Thus, the LCD devices have graduallyreplaced CRTs and increasingly become as the preferred display devicefor information processing equipment in the recent times.

Generally, an LCD device includes a lower substrate having a thin filmtransistor and a pixel electrode thereon, an upper substrate having acolor filter layer of red (R), green (G) and glue (B) colors thereon,and a liquid crystal layer interposed between the lower and uppersubstrates. Upon fabricating a liquid crystal panel by boning the lowerand upper substrates, driving signal, e.g., gate signal, and data signalare applied to the liquid crystal panel region to generate an electricfield on the pixel electrode, and the generated electric field twistsliquid crystal molecules to adjust transmissivity of light emitted froma backlight, thereby implementing (displaying) images.

FIG. 1 is a plane view schematic diagram illustrating an LCD deviceaccording to the related art. As shown in FIG. 1, a plurality of gatelines 24 are arranged to cross a plurality of data lines 25 in aperpendicular manner on a lower substrate 10, thereby defining aplurality of pixel regions. A pixel electrode 23 is arranged in each ofthe plurality of pixel regions. A thin film transistor (TFT) which is aswitching device is arranged at each intersection between the gate lines24 and the data lines 25. Also, a gate pad 24 a and a data pad 25 a areelectrically connected to one of the ends of the gate lines 24 and thedata lines 25, respectively, to receive applied driving signal and datasignal generated from a printed circuit board.

An upper substrate 40 has a common electrode (not shown) arranged at aregion corresponding to an active region 21 of the LCD device andoverlapping the pixel electrode. The common electrode receives a commonvoltage applied from an exterior via a common voltage line 30. The lowersubstrate 10 and the upper substrate 40 are bonded at their edges with asealant 50.

FIG. 2 is an exploded view schematic diagram of region A shown inFIG. 1. As shown in FIG. 2, the sealant 50 is printed on the region onwhich the common voltage line 30 is located to form seal lines (shown bydashed lines). The sealant 50, which is used to bond the lower substrate10 and the upper substrate 40, overlaps the common voltage line 30(shown as shaded).

FIG. 3 is a cross-sectional view schematic diagram along I-I′ of FIG. 1.As shown in FIG. 3, the common voltage line 30 is formed on the lowersubstrate 10. The sealant 50 is coated on the common voltage line 30 tobond the lower substrate 10 and the upper substrate 40 together. Thesealant 50 contains conductive balls 56. The conductive balls 56 come incontact with the common voltage line 30 on the lower substrate 10 andthe common electrode 44 on the upper substrate 40 and supply a commonvoltage signal applied to the common voltage line 30 to E the commonelectrode 44.

As such, the LCD device according to the related art employs theconductive balls 56 in the sealant 50 to supply the common voltagesignal to the common electrode 44 on the upper substrate 40. Thus, thesealant 50 needs to overlap the common voltage line 30. However, the LCDdevice having such a structure may encounter the following problems.

An LCD device commonly undergoes an inspection for determining whetherproduction defects are presented. The inspection commonly is performednot only in each production process but after the completion of theproduction process of the LCD device. Thus, the inspection of thesealant of the LCD device is performed not only at the sealant printingprocess but after the completion of the production process of the LCDdevice. During the inspection of the sealant at the sealant printingprocess, an assessment is made as to whether a preset amount of asealant material has been printed.

In addition, the inspection of the sealant after the completion of theproduction process of the LCD device is performed on the sealant as itbonds the lower substrate 10 and the upper substrate 40 together. Thus,such an inspection of the sealant after the completion of the LCDproduction process is performed by a visual inspection. For example, thesealant is visually observed to inspect whether a line width of thesealant is non-uniform, whether the sealant has a crack or whether thesealant is partially separated.

However, the LCD device according to the related art employs theconductive balls in the sealant and has the sealant overlap the commonvoltage line. As a result, a visual inspection cannot be performedeffectively on the sealant after the completion of the LCD productionprocess due to the common voltage line formed of an opaque metal and theoverlap between the common voltage line and the sealant.

SUMMARY OF THE INVENTION

Accordingly, embodiments of the invention is directed to a liquidcrystal display device that substantially obviates one or more of theproblems due to limitations and disadvantages of the related art.

An object of the embodiments of the invention is to provide a liquidcrystal display device that allows effective visual inspections of asealant and prevents defect generations in a sealant.

Another object of embodiments of the invention is to provide a liquidcrystal display device capable of visually observing a line width of asealant through an observation region in a common voltage line.

Another object of embodiments of the invention is to provide a liquidcrystal display device capable of visually observing a sealant through apartially etching region in a common voltage line.

Additional features and advantages of embodiments of the invention willbe set forth in the description which follows, and in part will beapparent from the description, or may be learned by practice ofembodiments of the invention. The objectives and other advantages of theembodiments of the invention will be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof embodiments of the invention, as embodied and broadly described, aliquid crystal display device includes a first electrode on a firstsubstrate, a second electrode and a third electrode on a secondsubstrate, the second electrode electrically contacting the firstelectrode at a first portion and the third electrode at a secondportion, and including a transparent conductive material, a sealantattaching the first and second substrates together in a sealant region,the sealant between the first and second electrodes and the sealantincluding a plurality of conductive balls for electrically connectingthe first and second electrodes; and a liquid crystal layer between theattached first and second substrates and within the sealant.

In another aspect, a liquid crystal display device includes a firstelectrode on a first substrate, a second electrode on a secondsubstrate, the first electrode facing the second electrode, a sealantattaching the first and second substrates together, the sealantincluding a plurality of conductive balls and an observation region, theconductive balls electrically connecting the first and second electrodesand the observation region corresponding to a region where the sealantextends substantially parallel to the first electrode and does notoverlap the first electrode; and a liquid crystal layer between theattached first and second substrates and within the sealant.

In another aspect, a liquid crystal display device includes a firstsubstrate including a pixel electrode and a common voltage line thereon,the common voltage line having a plurality of etched portions, a secondsubstrate including a common electrode thereon, the common electrodefacing the pixel electrode in an active region of the device, and asealant attaching the first and second substrates together, the sealantincluding a plurality of conductive balls and the conductive balls inelectrical contact with the common voltage line and the commonelectrode, wherein the etched portions of the common voltage lineprovide a visual view of the sealant from the first substrate.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of embodiments of the inventionas claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of embodiments of the invention and are incorporated inand constitute a part of this specification, illustrate embodiments ofthe invention and together with the description serve to explain theprinciples of embodiments of the invention. In the drawings:

FIG. 1 is a plane view schematic diagram illustrating an LCD deviceaccording to the related art;

FIG. 2 is an exploded view schematic diagram of region A shown in FIG.1;

FIG. 3 is a cross-sectional view schematic diagram along I-I′ of FIG. 1;

FIG. 4A is a plane view schematic diagram illustrating an LCD device inaccordance with a first embodiment of the invention;

FIG. 4B is an exploded view schematic diagram of region B shown in FIG.4A;

FIGS. 5 and 6 are sectional views showing the structure of pixel of thefirst embodiment of present LCD device;

FIG. 7 is a plane view schematic diagram illustrating an LCD device inaccordance with a second embodiment of the invention;

FIGS. 8A and 8B are sectional views showing the structure of sealingunit of the second embodiment of the present LCD device;

FIG. 9 is a plane view schematic diagram illustrating an LCD device inaccordance with a third embodiment of the invention;

FIG. 10 is an exploded view schematic diagram of region C shown in FIG.9;

FIGS. 11 and 11B are sectional views showing the structure of sealingunit of the third embodiment of the present LCD device;

FIG. 12A-12C are views showing the modifications of the third embodimentof this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings.

FIGS. 4A and 4B are plane view schematic diagram illustrating an LCDdevice in accordance with a first embodiment of the invention. In FIG.4A, an LCD device includes a lower substrate 110, an upper substrate 140and a liquid crystal layer (not shown) interposed between the lower andupper substrates 110 and 140. The lower substrate 110 is bonded onto theupper substrate 140 by a sealant 150. The sealant 150 may be printed orcoated by a screen printing method or a dispensing method on one or bothof the lower substrate 110 or the upper substrate 140.

The lower substrate 110 includes a plurality of gate lines 124 and datalines 125 arranged thereon and defining a plurality of pixel regions.The lower substrate 110 also includes pixel electrodes 123 arrangedtherein the pixel regions and a thin film transistor (TFT) arranged ineach of the pixel regions. Accordingly, by applying a signal to the TFTfrom the exterior via the gate lines 124, the TFT is controlled toselectively apply an image signal inputted via the data line 125 to thepixel electrode 123.

Also, a gate pad 124 a and a data pad 125 a are electrically connectedto one of the ends of the gate lines 124 and the data lines 125 tosupply signals from the exterior to the gate lines 124 and the datalines 125, respectively. The upper substrate 140 includes a commonelectrode (not shown) arranged at an active region 121 of the LCD deviceand facing the pixel electrodes 123 in each pixel region. A commonvoltage is applied to the common electrode via a common voltage line 130to form an electric field across the common electrode and the pixelelectrode 123.

Although not shown detail in figure, a gate tap carrier package (TCP)and a data TCP are attached to the lower substrate 110. The gate TCP andthe data TCP respectively have a gate driving IC and a data driving ICmounted therein. The gate TCP and the data TCP respectively supply ascanning signal and an image signal to a gate pad 124 a and a data pad125 a arranged on the lower substrate 110. Also, the data TCP 180 b mayfurther include various circuits, such as a common voltage generatingcircuit. The common voltage generating circuit is electrically connectedto the common voltage line 130 on the lower substrate 110 to apply acommon voltage to the common voltage line 130.

In addition, the common voltage line 130 is arranged along two edges ofthe lower substrate 110. Alternatively, the common voltage line 130 maybe arranged differently, for example, along three edges or all edges ofthe lower substrate 100. Further, the sealant 150 is arranged on edgesof one or both of the lower substrate 110 and the upper substrate 140 tobond the lower and upper substrates 110 and 140 together.

As shown in FIG. 4B, the common voltage line 130 is apart from thesealant 150 in the predetermined distance and a conductive line 135 isdisposed between the common voltage line 130 and the sealant 150 so thatthe conductive line 135 is overlapped with at least a part of the commonvoltage line 130 and the sealant 150. The conductive line 135 is made ofa transparent material such as a indium tin oxide and a tin zinc oxide.

The sealant 150 is connected to the common electrode on the uppersubstrate 140 and contains a plurality of conductive balls. Theconductive line 135 is overlapped and connected with the common voltageline 130 and the sealant 150 and thus the common voltage supplied to thecommon voltage line 130 is applied to the common electrode of the uppersubstrate 140 through the conductive line 135 and the sealant 150. Atthat time, since the conductive line 135 has a width broader than thatof the sealant 150, the conductive line 135 may be overlapped with thewhole area of the sealant 150 or a part of the sealant 150.

Since the conductive line 135 is transparent, it is possible to observethe sealant 150 corresponding to the conductive lien 135 by theoperator's eye. That is, the operator can observe the shape of thesealant 150 by his eye to detect the width and inferiority of thesealant 150.

The sealant 150 is disposed on the conductive line 135 to connect thesealant 150 with the conductive line 135. Further, the common voltageline 130 is formed on the different layer from the conductive line 135and connected to the conductive line 130 through a contact hole formedin the insulating layer between the common voltage line 130 and theconductive line 135.

FIGS. 5 and 6 are sectional views showing the LCD device according tothe first embodiment of the present invention. At this time, FIG. 5indicates the LCD device having a TFT (thin film transistor) of bottomgate type and FIG. 6 indicates the LCD device having a TFT of top gatetype. In figures, the LCD device is divided into pixel unit and sealingunit for convenience.

Referring to FIG. 5, the LCD device includes a lower substrate 110 andan upper substrate 140. On the lower substrate, a gate electrode 172 isformed in the pixel unit and the common voltage line 130 is formed inthe sealing unit. The gate electrode 172 and the common voltage line 130may be made by the different processes. However, it is proper to formthe gate electrode 172 and the common voltage line 130 with same metalby the same process.

A gate insulating layer 182 is formed on the lower substrate 110 and asemiconductor layer 174 such as a-Si is formed on the gate insulatinglayer 182 in the pixel unit. Further, a source electrode 176 and a drainelectrode 177 are formed on the semiconductor layer 174, and apassivation layer 184 is formed on the whole area of the lower substrate184.

On the passivation layer 184, a pixel electrode 123 is formed in thepixel unit and the conductive line 135 is formed on the sealing unit.The pixel electrode 123 and the conductive line 135 may be formed by thedifferent processes. However, it is proper to form pixel electrode 123and the conductive line 135 with same material such as indium tin oxideand indium zinc oxide by the same process. Contact holes are formed inthe passivation layer 184 at the pixel unit and sealing unit, so thatthe pixel electrode 123 is connected to the drain electrode 177 throughthe contact hole of the passivation layer 184 in the pixel unit and theconductive line 135 is connected to the common voltage line 130 throughthe contact hole of the passivation layer 184 in the sealing unit.

In the sealing unit, the sealant 150 is formed. Since the sealant 150 isformed on the common voltage line 130, the conductive ball 156 containedin the sealant 150 is contacted with the common voltage line 130 toconnect electrically the conductive ball 156 to the common voltage line130. Although the a part of sealant 150 is overlapped and connected withthe common voltage line 130, the common voltage line 130 may be formedin the width larger than from that of the sealant 150 to overlap thecommon voltage line 130 with the whole width of the sealant 150.

A black matrix 141 is formed in the pixel unit and the sealing unit onthe upper substrate 140. The black matrix is disposed in the non-displayregion such as TFT forming region, the gate line region, and the dataline region to block the light through the non-display region. A colorfilter layer 142 is formed on the upper substrate 140 and a commonelectrode 144 made of the transparent material such as indium tin oxideand indium zinc oxide on the color filter layer 142 of the pixel unitand the black matrix 141 of the sealing unit.

The lower and upper substrates 110 and 140 are attached each other bythe sealant 150 of the sealing unit and a liquid crystal layer 160 isformed between the lower and upper substrates 110 and 140.

The conductive ball 156 in the sealant 150 is contacted with the commonelectrode 144 in the sealing unit. Thus, the common voltage line 130 inthe lower substrate 110 is connected to the common electrode 144 in theupper substrate 140 through the conductive line 135 and the conductiveball 156. When the common voltage is supplied from the outer driver (notshown), the common voltage is applied to the common voltage 144 of theupper substrate 140 through the common voltage line 130, the conductiveline 135, and the conductive ball 156 to generate the electric fieldbetween the common electrode 144 and the pixel electrode 123.

In this embodiment, the transparent conductive line 135 is disposedbetween the common voltage line 130 and the sealant 150 to connect theconductive line 135 to the common voltage line 130 and the sealant 150.Thus, since the sealant 150 is overlapped with the transparentconductive line 135, not the opaque common voltage line 130, the shapeof the sealant 150 may be observe by the operator through thetransparent conductive line 135 and as a result the width andinferiority of the sealant 150 can be detected.

We will describe the TFT of top gate type in the FIG. 6 as follow. Atthis time, the description for the structure shown in FIG. 5 will beomitted.

As shown in FIG. 6, the semiconductor layer 174 is formed in the pixelunit on the lower substrate 110. The semiconductor layer 174 is formedwith a poly-crystalline silicon (p-Si) or the a-Si. An impurities areinjected in the both sides of the semiconductor to form an ohmic contactlayer.

The gate insulating layer 182 is formed on the whole area of the lowersubstrate 110. A gate electrode 172 is formed in the pixel unit on thegate insulating layer 182 and the common voltage line 130 is formed inthe sealing unit on the gate insulating layer 182. The gate electrode172 and the common voltage line 130 may be made by the differentprocesses. However, it is proper to form the gate electrode 172 and thecommon voltage line 130 with same metal by the same process.

Over the lower substrate 110 on which the gate electrode 172 and thecommon voltage line 130 are formed, an interlayer 183 is deposited. Thesource electrode 176 and the drain electrode 177 are formed in the pixelunit on the interlayer 183 and the passivation layer 184 is formed overthe whole area of the lower substrate 110. The source electrode 176 andthe drain electrode 177 are connected to the semiconductor layer 174through the contact hole formed in the gate insulating layer 182 and theinterlayer 183.

On the passivation layer 184, the pixel electrode 123 is formed in thepixel unit and the conductive line 135 is formed in the sealing unit.The pixel electrode 123 and the conductive line 135 which are formedwith the transparent material such as the indium tin oxide or the indiumzinc oxide are respectively connected to the drain electrode 177 and thecommon voltage line 130 through the contact holes formed in thepassivation layer 184.

The black matrix 141 is formed in the pixel unit and the sealing unit onthe upper substrate 140 and the color filter layer 142 is formed in thepixel unit on the upper substrate 140. Further, the common electrode 144which is made of the transparent material such as the indium tin oxideand the indium zinc oxide is disposed on the color filter layer 142 inthe pixel unit and on the common electrode 144 in the sealing unit.

In the sealing unit on the lower substrate 110, the sealant 150 isformed to attach the lower and upper substrates 110 and 140. The sealant150 is disposed on the common voltage line 130, so that the conductiveball 156 of the sealant 150 is contacted with the conductive line 135 ofthe lower substrate 110 and the common electrode 144 of the uppersubstrate 140 to connect electrically the common voltage line 130 andthe common electrode 144.

In this embodiment, since the sealant 150 is overlapped with thetransparent conductive line 135, not the opaque common voltage line 130,the shape of the sealant 150 may be observed by the operator through thetransparent conductive line 135 and as a result the width andinferiority of the sealant 150 can be detected.

FIG. 7 is a view showing the LCD device according to the secondembodiment of the present invention. At this time, we will describe onlythe different structure from the first embodiment, not the same elementas the first embodiment.

As shown in FIG. 7, in this embodiment, the common voltage line 230 ismade of the transparent material and directly contact with the sealant250. That is, the common voltage line 230 is superposed with the sealant250. Since the common voltage line 230 is made of the transparentmaterial such as the indium tin oxide or the indium zinc oxide, theshape of the sealant 250 may be observed by the operator through thetransparent common voltage line 230. FIGS. 8A and 8B are the sectionalviews along B-B′ line of FIG. 7 showing the structure of the sealingunit of the LCD device. At this time, FIG. 8A indicates the LCD devicehaving a TFT (thin film transistor) of bottom gate type and FIG. 8Bindicates the LCD device having a TFT of top gate type.

As shown in FIG. 8A, in the LCD device having TFT of bottom gate type,the common voltage line 230 made of the transparent conductive materialis formed on the lower substrate 210. At this time, the gate insulatinglayer 282 and the passivation layer 284 upper the common voltage line230 is removed to expose the common voltage line 230. The sealant 250 isformed on the expose region of the common voltage line 230. Theconductive ball 256 of the sealant 250 is contacted with the commonvoltage line 230 and the common electrode 244 in the upper substrate 240to connect electrically the common voltage line 230 and the commonelectrode 244. Thus, the common voltage supplied to the common voltageline 230 is applied to the common electrode 244 through the conductiveball 256.

As shown in FIG. 8B, in the LCD device having TFT of top gate type, thecommon voltage line 230 made of the transparent conductive material suchas the indium tin oxide and the thin zinc oxide is formed on the gateinsulating layer 282. At this time, the interlayer 283 and thepassivation layer 284 upper the common voltage line 230 is removed toexpose the common voltage line 230. The sealant 250 is formed on theexpose region of the common voltage line 230, so that the common voltageline 230 is electrically connected to the common electrode 244 by theconductive ball 156.

Since the transparent common voltage line 230 is contacted with thesealant 250, the shape of the sealant 250 may be observed by theoperator through the transparent common voltage line 230.

In this invention, as described above, the transparent common voltageline is directly connected to the sealant or the opaque common voltageline is connected to the sealant though the transparent conductive lineto apply the common voltage to the common electrode. Thus, the sealant250 may be detected through the transparent layer, i.e., the commonvoltage line or the conductive line.

Also, the observation of the sealant may be performed after bonding thelower substrate and the upper substrate together. For example, after thecompletion of the fabrication process of a liquid crystal displaymodule, the line width of the sealant is inspected in an overall moduleinspection process.

Accordingly, although the line width of the sealant may pass aninspection at the sealant printing process, if the inspection made afterthe completion of the fabrication process of the LCD module finds theline width being less than a preset line width or any line-width defectis generated at the line width (e.g., introduction of foreign materialor cracks or holes on a coated sealant), the complete LCD module wouldbe determined as a defective one. As a result, the product undergoes amore stringent inspection and defects in finished products areprevented.

FIG. 9 is a plan view showing the LCD device according to the thirdembodiment of this invention and FIG. 10 is an partially enlarged planview of C-region of FIG. 9. In this embodiment, the common voltage lineis made of the opaque metal and directly contacted with the sealant. Inorder to observe the shape of the sealant, in this invention, the windowfor observing the sealant is formed in the opaque common voltage line.This structure is described in detail as follow.

As shown in FIG. 9, the common voltage line 330 is formed along twosides, three sides, or all sides of the lower substrate 310, and thesealant 350 is formed in the outside of the lower and upper substrates310 and 340 to attach thereof. The common voltage line 330 is made ofopaque metal and the sealant 350 is overlapped with a part of the commonvoltage line 330.

As shown in FIG. 10, the common voltage line 330 includes a plurality ofprotrusions 330 b protruded from a main common voltage line portion 330a. The sealant 350 is arranged on the common voltage line 330 andoverlaps the common voltage line 330. The sealant 350 has a widthsmaller than that of the protrusions 330 b so that the sealant 350 isentirely overlapped with the protrusions 330 b. At this time, thesealant 350 can be formed in the width larger than that of theprotrusions 330 b so that the sealant 350 can be overlapped with the apart of the main common voltage line 330 a and the protrusions 330 b.

The conductive ball in the sealant 350 is contacted with the protrusions330 b to connect electrically the common voltage line 330 to the sealant350 and a result the common voltage is applied to the common electrodein the upper substrate 340.

The protrusions 330 b may be arranged with a preset width and a presetinterval. Therefore, the LCD device according to this embodiment of theinvention, unlike an LCD device of the related art, includes an opening,in the common voltage line 330, where no metal or an opaque material isdisposed. The opening may correspond to a region between two protrusions330 b of the common voltage line 330. In addition, the opening forms atransmittable region to allow visual inspections, for example, a regionfor inspecting a line width of the sealant 350 that is arranged on thecommon voltage line 330. Accordingly, an operator can visually observethe shape of the sealant 350 through the opening, thereby inspecting theline width of the sealant 350 and any defect generation.

FIGS. 11A and 11B are sectional views along line C-C′ of FIG. 10. Atthat time, FIG. 11A indicates the LCD device having a TFT (thin filmtransistor) of bottom gate type and FIG. 11B indicates the LCD devicehaving a TFT of top gate type.

As shown in FIG. 11A, in the LCD device of the bottom gate type, theprotrusions 330 b of the common voltage line 330 is formed on the lowersubstrate 310. Although not shown, the main common voltage line 330 aconnected to the protrusions 330 b is formed on the lower substrate 310.Since, the common voltage line 330 may be formed of the same metal asthe source and drain electrodes and by the same fabrication process. Forexample, the protrusions 330 b and the main common voltage line 330 acan be formed by laminating a metal of an uniform width and thenpartially etching the laminated the metal by a photolithography.

The gate insulating layer 382 and the passivation layer 384 over theprotrusions 330 b are removed to expose the protrusions 330 b and thesealant 350 is formed on exposed protrusions 330 b so that theconductive ball 356 of the sealant 350 is contacted with the protrusions330 b. Further, the conductive ball 356 is contacted with the commonelectrode 344 in the upper substrate 340. Thus, the common voltage line330 is connected to the common electrode 344 through the conductive ball356 of the sealant 350.

As shown in FIG. 11B, in the LCD device of the bottom gate type, theprotrusions 33 ob are formed on the gate insulating layer 382 and theinterlayer 383 and the passivation layer 384 on the protrusions 330 bare removed to expose the protrusions 330 b. The sealant 350 is disposedon the exposed protrusions 330 b to contact the conductive ball 356 ofthe sealant 350 with the protrusions 330 b and as a result the commonvoltage line 330 is electrically connected to the common voltage.

As described above, the third embodiment of the invention includes alight-transmittable observation region 331 formed by partially etchingthe common voltage line 330 and a visual inspection of the sealant 350can be made through the observation region 331 in the common voltageline 330.

In embodiment, the sealant 350 is directly overlapped with the opaquecommon voltage line 330 to connect electrically the common voltage line330 in the lower substrate 310 to the common electrode 344 in the uppersubstrate 340. At this time, the protrusions 330 b of the common voltageline 330 is connecting line for connecting the common voltage line 330and the common electrode 344 and the main common voltage line 330 a is avoltage applying line to which the voltage is applied.

In this embodiment, the observing region 331 is formed in the opaquecommon voltage line 330 to observe the shape of the sealant 350 throughthe observation region 331. Thus, this embodiment is applicable to themodifications having the various structure if the observation region isprovided to the common voltage line.

FIG. 12A-12C are views showing the modifications of the third embodimentof this invention.

As shown in FIG. 12A, the common voltage line 330 may be formed in azigzag shape with a certain width. The common voltage line 330 includesan observation region 331 between the changes of the line direction toallow a visual observation of a sealant 350 printed on the commonvoltage line 230.

As shown in FIG. 12B, protrusions of the common voltage line 330 may bearranged at non-perpendicular with respect to the main line direction.The common voltage line 330 includes an observation region 331 betweentwo protrusions to allow the visual observation of the sealant 350printed on the common voltage line 330.

As shown in FIG. 12C, the common voltage line 330 includes a pluralityof windows 332 within its main line portion. The common voltage line 330includes the window to allow the visual observation of the sealant 350printed on the common voltage line 330. The window 332 may be formed ina rectangular shape as shown in FIG. 7C, but may have other shapes, suchas a circular shape or a triangular shape.

As described above, according to an embodiment of the invention, thecommon line is made of transparent material or includes a plurality ofprotrusions and observation regions. Alternatively, according to anembodiment of the invention, a transparent electrode electricallyconnects conductive balls of the sealant and the common voltage line inregions where the sealant and the common voltage line extend parallel toone another. As such, according to an embodiment of the invention, anLCD module includes an observation region to allow a visual inspectionof a sealant that may be otherwise blocked by the common voltage line.Thus, according to an embodiment of the invention, an effective visualinspection of a sealant can be performed after the completion of thefabrication process of an LCD module and an LCD module having afabrication defect, such as a bonding defect or sealant line-widthdefect, can be detected, thereby preventing weak bonding of thesubstrates or liquid crystal leakage.

The line shapes shown in figures are merely exemplary. For example, thecommon voltage line according to an embodiment of the invention may havea different structure from those shown in the figures. Therefore, anembodiment of the invention may not be limited to the illustratedshapes, but can also be implemented in various shapes. In addition, thedetailed explanation described above has been provided for a certain LCDdevice, but the present invention may not be limited to the LCD devicehaving the construction as shown. The present invention may beapplicable to LCD devices in which a common electrode is formed on anupper substrate and a common voltage is applied to the common electrodevia conductive balls contained in sealant.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the liquid crystal displaydevice of embodiments of the invention without departing from the spiritor scope of the invention. Thus, it is intended that embodiments of theinvention cover the modifications and variations of this inventionprovided they come within the scope of the appended claims and theirequivalents.

1. A liquid crystal display device comprising: a first electrode on afirst substrate; a second electrode and a third electrode on a secondsubstrate, the second electrode overlapping the first electrode at afirst portion, electrically contacting the third electrode at a secondportion, and including a transparent conductive material; a sealantattaching the first and second substrates together in a sealant region,the sealant between the first and second electrodes and the sealantincluding a plurality of conductive balls for electrically connectingthe first and second electrodes; and a liquid crystal layer between theattached first and second substrates and within the sealant.
 2. Thedevice according to claim 1, wherein the third electrode is directly onthe second substrate.
 3. The device according to claim 1, wherein thethird electrode is on at least one insulating layer.
 4. The deviceaccording to claim 1, wherein the second electrode contacts the thirdelectrode through a contact hole in at least one insulating layer on thesecond substrate.
 5. The device according to claim 1, wherein the secondelectrode electrically connects the conductive balls of the sealant andthe third electrode.
 6. The device according to claim 1, wherein thesecond electrode is in a region where the sealant and the thirdelectrode extend substantially parallel to one another.
 7. The deviceaccording to claim 1, wherein the first and third electrodes include anon-transparent conductive material.
 8. A liquid crystal display devicecomprising: a first electrode on a first substrate; a second electrodeon a second substrate, the first electrode facing the second electrode;a sealant attaching the first and second substrates together, thesealant including a plurality of conductive balls and an observationregion, the conductive balls electrically connecting the first andsecond electrodes and the observation region corresponding to a regionwhere the sealant extends substantially parallel to the first electrodeand does not overlap the first electrode; and a liquid crystal layerbetween the attached first and second substrates and within the sealant.9. The device according to claim 8, wherein the first electrode includesa plurality of protrusions extending from a main line portion, and theobservation region corresponds to the region between two of theimmediately adjacent protrusions of the first electrode.
 10. The deviceaccording to claim 9, wherein the protrusions extend perpendicularlyfrom the main line portion.
 11. The device according to claim 9, whereinthe protrusions extend at a non-90° angle from the main line portion.12. The device according to claim 8, wherein the first electrodeincludes a plurality of windows and the observation region correspondsto the windows.
 13. The device according to claim 8, wherein the firstelectrode has a zigzag shape.
 14. The device according to claim 8,further comprising: a common voltage source selectively applying acommon voltage to the second electrode through the first electrode andthe sealant.
 15. The device according to claim 8, wherein the firstsubstrate includes a pixel electrode in a pixel region, wherein thesecond electrode faces the pixel electrode in the pixel region.
 16. Thedevice according to claim 8, wherein the first electrode is arranged ina winding manner arranged along at least one edge of the liquid crystaldisplay device.
 17. The device according to claim 8, wherein the firstand second electrodes include a non-transparent conductive material. 18.A liquid crystal display device comprising: a first substrate includinga pixel electrode and a common voltage line thereon, the common voltageline having a plurality of etched portions; a second substrate includinga common electrode thereon, the common electrode facing the pixelelectrode in an active region of the device; and a sealant attaching thefirst and second substrates together, the sealant including a pluralityof conductive balls and the conductive balls in electrical contact withthe common voltage line and the common electrode, wherein the etchedportions of the common voltage line provide a visual view of the sealantfrom the first substrate.
 19. The device according to claim 18, whereinthe etched portions are formed along a main line portion of the commonvoltage line and forming a plurality of protrusions extending from themain line portion.
 20. The device according to claim 18, wherein theetched portions correspond to a plurality of windows in the commonvoltage line.